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Tube amp static crackle on certain notes?

Discussion in 'Amp Central Station' started by Paulie13, Feb 19, 2010.

  1. Paulie13

    Paulie13 Tele-Holic

    582
    Feb 16, 2009
    Atlanta
    When I turn my tube amp louder there is a "crackly-static" sound that gets worse and worse as the volume goes up. I played the same guitar, cables, and effects with a second amp and there was no problems. Any ideas on what to do to fix this?

    It kind of sounds like when you are putting the cable close to the input jack in when the amp is on.
     
  2. PaisleyRocks

    PaisleyRocks Tele-Holic

    550
    Oct 12, 2007
    Chattanooga
    Loose tube would be my guess.
     
  3. scoots

    scoots Tele-Holic

    806
    Jun 26, 2007
    hinckley,mn
    couldn't say exactly, but it sounds tube-ish to me as well, maybe one getting tired
     
  4. woodman

    woodman Grand Wazoo @ The Woodshed Gold Supporter

    Age:
    72
    Nov 28, 2004
    Mint Hill, NC
    That happened to me a long time ago (long before you were born! :D) and if i remember correctly, it was a crapped-out solder joint ... unfortunately, many of my memories from that era are fuzzy around the edges!
     
    Evil Funk and trouserpress like this.
  5. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    Dirty tube socket, bad solder connection/s, bad tube.....many possibilities.
     
    BobbyZ and Obelisk like this.
  6. woodman

    woodman Grand Wazoo @ The Woodshed Gold Supporter

    Age:
    72
    Nov 28, 2004
    Mint Hill, NC
    If your tubes have been in a long time, it's worth going to Rat Shack and buying some electronics cleaner to scour your tube pins — i once thought i had a tube going out, cleaned the pins, and the oxidation on them turned out to be the problem
     
  7. Wally

    Wally Telefied Ad Free Member

    Mar 17, 2003
    Lubbock, TX
    If you don't some cleaner handy, sometimes simply working the tubes in and out of the sockets a few times will re-establish good contacts.
     
    Last edited: Feb 19, 2010
  8. bo

    bo Friend of Leo's

    Mar 17, 2003
    Arlington, VA
    Last time that happened to me it was a bad preamp tube. YMMV.
     
  9. Paulie13

    Paulie13 Tele-Holic

    582
    Feb 16, 2009
    Atlanta
    I do have some De-oxit, should I spray the pins and reinsert them?
     
  10. Tele-writer

    Tele-writer Tele-Meister

    spray the sockets as well as the pins
     
  11. jefrs

    jefrs Doctor of Teleocity

    Nov 20, 2007
    Newbury, England
    One of my amps is producing a buzz on bottom G to B. So after fruitlessly trying a few other things, I fed its output to another speaker and the buzzing stopped. I fed another amp into its speaker and got the buzzings again. Conclusion, the combo box rattles.
     
  12. robt57

    robt57 Telefied Ad Free Member

    Feb 29, 2004
    Portland, OR
    Clean the tube pins with a good tuner cleaner. Tap the tube with the eraser of a pencil while completely warmed up. If yo are lucky, it won't be what I think it more probably is. Which quite possibly is a bad solder connection, or a CAP failing or both.
     
    trouserpress likes this.
  13. ThermionicScott

    ThermionicScott Poster Extraordinaire

    Age:
    38
    Dec 3, 2005
    SW CR IA US NA PE
    Wipe off the pins with a clean paper towel between insertions so you're not just moving the schmutz around in the sockets.
     
  14. sthebluesman

    sthebluesman TDPRI Member

    53
    Oct 23, 2007
    New Orleans area
    De-Oxit is a miracle. Definely try that. Sometimes I will take the chassis out and put a paper towel on the wire side of the socket to keep the spray from going everywhere, then I spray De-Oxit into each socket hole. The cleaner method is spraying the tube pins and inserting and removing them a few times. The pencil eraser tapping is a good trick to see if a tube is microphonic and possibly bad. Microphonic tubes will make strange sounds when they vibrate at higher volumes. I've had this problem on my old Tweed amps, but after a little wiggling and cleaning, it seems to go away.

    You can also pull the chassis, turn it on with the speakers hooked up, and tap around the wires and sockets with a chop stick to see if you find a bad connection. If all fails, change the tubes one by one and play it to see if the problem goes away. Be careful, and always just use one hand on the chassis when you are tapping with the chop stick. Try not to touch the chassis at all preferably.
     
  15. robt57

    robt57 Telefied Ad Free Member

    Feb 29, 2004
    Portland, OR

    Keep one hand IN YOUR BACK POCKET!
     
  16. jefrs

    jefrs Doctor of Teleocity

    Nov 20, 2007
    Newbury, England
    Keeping one hand in your pocket is for electronic engineers who know what they are doing. If you don't what you're doing, keep both hands in your pockets.
     
  17. Paulie13

    Paulie13 Tele-Holic

    582
    Feb 16, 2009
    Atlanta
    Brand new EL84s took care of the problem, but there was a horrible smell to them after I put them in. This was never there before. It seemed to get a little better over time, so I am going to go home tonight and see if its still happening.
     
  18. robt57

    robt57 Telefied Ad Free Member

    Feb 29, 2004
    Portland, OR

    True, but I trey to fix any/everything.

    Just last night I pulled my backup Stage 16o apart for that same reason, it would even buzz loudly an you had to shut it off and turn it back on or whack it. Just recently started doing that, but previously it woud just loose volume for a few seconds, mostly at super clean bassey setting.

    The main Caps solder joints had cracked, so a little flux and some heat with my old soldering iron with the small tip installed... fixed. Combo amps with a lot of power is a bad design idea IMO, vibrates the thing eventually to pieces... ;) Had the same exact thing happen to a Flextone I used to have. Easy fix, and discharging CAPs is not rocket science exactly, as long as you discharge them with out the juice straying to you or some poor unsuspecting component next to them I figure... ;)

    I sure would not have invested the $90.00 minimum estimate I got for the 'usual those amp do' according to the amp tech I emailed into that amp.

    I really keep my left arm away, but my wife sez I have no heart on that side either...
     
  19. trouserpress

    trouserpress Tele-Meister

    Age:
    55
    452
    May 4, 2015
    Leipzig
    I know I'm penetrating a zombie here but I just want to share an unmentioned cause of those very symptoms I encountered today:
    A defective jack plug for the speaker connector with a shunt pin that would try to short-out the circuit whenever any #c was played!
     
    Wally likes this.
  20. schmee

    schmee Friend of Leo's

    Jun 2, 2003
    northwest
    Cold solder joint. Just reflow them all.
    Bad tube socket.
     
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